adds ability to set hint on Parse.Query #6288 (#6322)

* added hint to aggregate

* added support for hint in query

* added else clause to aggregate

* fixed tests

* updated tests

* Add tests and clean up

* Add support for explain

Co-authored-by: Diamond Lewis <findlewis@gmail.com>

spec/ParseQuery.hint.spec.js

@@ -0,0 +1,170 @@
+'use strict';
+
+const Config = require('../lib/Config');
+const TestUtils = require('../lib/TestUtils');
+const request = require('../lib/request');
+
+let config;
+
+const masterKeyHeaders = {
+  'X-Parse-Application-Id': 'test',
+  'X-Parse-Rest-API-Key': 'rest',
+  'X-Parse-Master-Key': 'test',
+  'Content-Type': 'application/json',
+};
+
+const masterKeyOptions = {
+  headers: masterKeyHeaders,
+  json: true,
+};
+
+describe_only_db('mongo')('Parse.Query hint', () => {
+  beforeEach(() => {
+    config = Config.get('test');
+  });
+
+  afterEach(async () => {
+    await config.database.schemaCache.clear();
+    await TestUtils.destroyAllDataPermanently(false);
+  });
+
+  it('query find with hint string', async () => {
+    const object = new TestObject();
+    await object.save();
+
+    const collection = await config.database.adapter._adaptiveCollection(
+      'TestObject'
+    );
+    let explain = await collection._rawFind(
+      { _id: object.id },
+      { explain: true }
+    );
+    expect(explain.queryPlanner.winningPlan.stage).toBe('IDHACK');
+    explain = await collection._rawFind(
+      { _id: object.id },
+      { hint: '_id_', explain: true }
+    );
+    expect(explain.queryPlanner.winningPlan.stage).toBe('FETCH');
+    expect(explain.queryPlanner.winningPlan.inputStage.indexName).toBe('_id_');
+  });
+
+  it('query find with hint object', async () => {
+    const object = new TestObject();
+    await object.save();
+
+    const collection = await config.database.adapter._adaptiveCollection(
+      'TestObject'
+    );
+    let explain = await collection._rawFind(
+      { _id: object.id },
+      { explain: true }
+    );
+    expect(explain.queryPlanner.winningPlan.stage).toBe('IDHACK');
+    explain = await collection._rawFind(
+      { _id: object.id },
+      { hint: { _id: 1 }, explain: true }
+    );
+    expect(explain.queryPlanner.winningPlan.stage).toBe('FETCH');
+    expect(explain.queryPlanner.winningPlan.inputStage.keyPattern).toEqual({
+      _id: 1,
+    });
+  });
+
+  it('query aggregate with hint string', async () => {
+    const object = new TestObject({ foo: 'bar' });
+    await object.save();
+
+    const collection = await config.database.adapter._adaptiveCollection(
+      'TestObject'
+    );
+    let result = await collection.aggregate([{ $group: { _id: '$foo' } }], {
+      explain: true,
+    });
+    let { queryPlanner } = result[0].stages[0].$cursor;
+    expect(queryPlanner.winningPlan.stage).toBe('COLLSCAN');
+
+    result = await collection.aggregate([{ $group: { _id: '$foo' } }], {
+      hint: '_id_',
+      explain: true,
+    });
+    queryPlanner = result[0].stages[0].$cursor.queryPlanner;
+    expect(queryPlanner.winningPlan.stage).toBe('FETCH');
+    expect(queryPlanner.winningPlan.inputStage.indexName).toBe('_id_');
+  });
+
+  it('query aggregate with hint object', async () => {
+    const object = new TestObject({ foo: 'bar' });
+    await object.save();
+
+    const collection = await config.database.adapter._adaptiveCollection(
+      'TestObject'
+    );
+    let result = await collection.aggregate([{ $group: { _id: '$foo' } }], {
+      explain: true,
+    });
+    let { queryPlanner } = result[0].stages[0].$cursor;
+    expect(queryPlanner.winningPlan.stage).toBe('COLLSCAN');
+
+    result = await collection.aggregate([{ $group: { _id: '$foo' } }], {
+      hint: { _id: 1 },
+      explain: true,
+    });
+    queryPlanner = result[0].stages[0].$cursor.queryPlanner;
+    expect(queryPlanner.winningPlan.stage).toBe('FETCH');
+    expect(queryPlanner.winningPlan.inputStage.keyPattern).toEqual({ _id: 1 });
+  });
+
+  it('query find with hint (rest)', async () => {
+    const object = new TestObject();
+    await object.save();
+    let options = Object.assign({}, masterKeyOptions, {
+      url: Parse.serverURL + '/classes/TestObject',
+      qs: {
+        explain: true,
+      },
+    });
+    let response = await request(options);
+    let explain = response.data.results;
+    expect(explain.queryPlanner.winningPlan.inputStage.stage).toBe('COLLSCAN');
+
+    options = Object.assign({}, masterKeyOptions, {
+      url: Parse.serverURL + '/classes/TestObject',
+      qs: {
+        explain: true,
+        hint: '_id_',
+      },
+    });
+    response = await request(options);
+    explain = response.data.results;
+    expect(
+      explain.queryPlanner.winningPlan.inputStage.inputStage.indexName
+    ).toBe('_id_');
+  });
+
+  it('query aggregate with hint (rest)', async () => {
+    const object = new TestObject({ foo: 'bar' });
+    await object.save();
+    let options = Object.assign({}, masterKeyOptions, {
+      url: Parse.serverURL + '/aggregate/TestObject',
+      qs: {
+        explain: true,
+        group: JSON.stringify({ objectId: '$foo' }),
+      },
+    });
+    let response = await request(options);
+    let { queryPlanner } = response.data.results[0].stages[0].$cursor;
+    expect(queryPlanner.winningPlan.stage).toBe('COLLSCAN');
+
+    options = Object.assign({}, masterKeyOptions, {
+      url: Parse.serverURL + '/aggregate/TestObject',
+      qs: {
+        explain: true,
+        hint: '_id_',
+        group: JSON.stringify({ objectId: '$foo' }),
+      },
+    });
+    response = await request(options);
+    queryPlanner = response.data.results[0].stages[0].$cursor.queryPlanner;
+    expect(queryPlanner.winningPlan.inputStage.keyPattern).toEqual({ _id: 1 });
+  });
+});